▲ The Geomunoreum lava tube system is one of Jeju's three locations to be designated as UNESCO World Natural Heritage Sites. Photo courtesy Jeju Special Self-Governing Province

The Geomunoreum lava tube system stands among Jeju’s 368 oreum (secondary volcanic cones) as a unique phenomenon both in its designation as a UNESCO World Natural Heritage Site and in the array of rare features it contains. Hiking the oreum, even without any knowledge of its unique geological features, is a fascinating trek into the mysteries of a place that has long intrigued local residents and visitors alike.

Local volunteers, who presently number around 120, care for Geomunoreum. Following the site’s designation as a UNESCO World Natural Heritage Site in 2007, the government created the infrastructure of trails, but now upkeep is done solely by volunteers, some of whom also serve as guides. Kim Sang Soo, village leader and guide, studied for two years before he began leading hikes on the oreum. According to local lore, each climb to the top will prolong one’s life by five years. Going by that, Kim estimates that, thus far, he should reach the ripe old age of 180. While some hikers may be frustrated that they are unable to explore the oreum independently, to do so would be missing the experience of hiking with a guide with a visceral connection to the land and a deep knowledge of this enigmatic place. Limiting access to the oreum also helps to preserve its fragile environment and minimize the impact of tourism.

Geomun is the Korean word for black and not only describes the color but connotes a divine presence as well. Thus, the word Geomunoreum means both black volcano and divine volcano. In addition to his expertise on the geological and environmental features of the oreum, Kim clearly encourages visitors to embrace the spiritual side of climbing the oreum. “Too many people hike very fast, they want to get to the top and that’s it,” he said. “They are missing so much of what is really the point of Geomunoreum: to stop, to really feel it, to breathe in this clean air and feel why we are here.”

Besides the intangible spiritual cleansing that may be a part of the hike, there is a literal aspect to the oreum’s breath as well, for among Geomunoreum’s many unique features are natural channels called punghyeol that emit streams of air that change temperature with the seasons: cool in the summer and warm in the winter. These channels contribute to a series of strange phenomenon that occur in the many microclimates on the oreum, such as unmelted snow well into springtime, trees and flowers that bloom at different times despite being next to one another, and leaves that sway in the wind while others nearby may remain completely still. Additionally, Geomunoreum is home to the Japanese Aucuba tree, which is well known as a natural air purifier.

From a far, Geomunoreum appears to be one volcanic cone but actually consists of nine peaks surrounding a horseshoe-shaped crater that is 4,400 meters in diameter at the rim and over 1,000 meters wide at the floor — nearly the size of Mount Halla’s crater. To some, the oreum resembles a giant water lily, while others claim that the nine peaks appear to be dragons playing with a stone that possesses the power to grant wishes. In the center, there is one small cone called Auoreum along with dozens of pit craters, which were caused by internal gas expansion during the lava flow.

Streams of lava flowing northeast toward the ocean 14.6 kilometers away created Geomunoreum’s tubes. As the lava flowed toward the sea, it created the Bengdwigul, Manjanggul, Gimnyeonggul, Yongcheondonggul and Dangcheomuldonggul lava tube systems as it cooled. Within Geomunoreum, there is a vertical lava tube extending over 35 meters deep that connects to a horizontal tube that runs for more than 48 meters under the surface of the oreum.

At times, the hiking trail passes over the tube and hikers who stamp their feet can feel the hollow tube underneath. The gotjawal, or ancient forests, on Geomunoreum remain relatively undisturbed by humans. From the peak, a distinction is clearly visible between the deciduous and evergreen forests dividing the oreum. An unusual feature of this strange primeval forest are the fallen yet living trees that wrap their roots around huge volcanic rocks and take moisture from the air rather than the soil. Due to the extremely rocky nature of the soil, root systems are very shallow. The shallow root systems combined with Jeju’s strong winds cause most of the trees to fall when they reach a certain size and height. Yet, these uprooted trees are still very much alive and continue to produce leaves every year.

The gotjawal is home to many important species of flora due to the complex microclimates on the oreum. While hiking, one can easily spot a plethora of wildflowers, including a rare kashi strawberry plant only found on Jeju, as well as many medicinal plants.

▲ Geomeunoreum's unique microclimates are home to rare and unusual species of flora. Photo courtesy Jeju Special Self-Goverining Province

Another unique feature of Geomunoreum is the presence of sumgol, or deep crevices in the rocks that channel and filter rainwater, eventually allowing it to reach aquifers deep beneath the ground that are the source of Jeju’s famously pure water.

While Geomunoreum has been relatively undisturbed by human activity, there are signs of habitation, including stone walls and mounds, as well as burial sites and a large charcoal kiln. Contrary to what the average hiker may assume based on their prehistoric appearance, these primitive structures were used as recently as the 1940s, until the presence of Japanese soldiers kept local villagers away from the oreum.

Along with these pastoral signs of human habitation, there are signs of a darker presence on the oreum as well. The Japanese army created tunnels used for storing ammunition and weapons, the longest of which is around 60 meters.

Kim explained that guiding hikes can get tricky, as some older Japanese tourists express a tinge of nationalistic pride upon seeing the tunnels, while older Korean hikers may be unable to hide their bitterness at the memory of the occupation.

Manjanggul is the longest lava tube on Jeju and one of the largest and best-preserved in the world, stretching approximately 7,400 meters and measuring 25 meters at its highest point, and 18 meters wide. It is also the only lava tube open to the public. Summer is an ideal time to visit as Manjanggul maintains a temperature of between 11 and 18 degrees Celsius and 87 percent humidity throughout the year.

Admission to Geomunoreum is free, but visitors must sign up for a guided tour at the Visitor Center. It takes roughly two hours to reach the crater, and about three hours to hike the entire course. Reservations must be made by calling the Visitor Center at 064-784-0456, and should be made at least two days prior to visiting. Manjanggul lava tube is open from 9 a.m. to 6 p.m. daily.

ⓒ Jeju Weekly 2009 (http://www.jejuweekly.com)
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